Rotor blade hub

ABSTRACT

The present invention concerns a rotor blade hub for a wind power installation. Such a hub represents a mechanical connection between the (horizontal) rotor shaft (rotor spindle) and the rotor blades. This means that all forces which occur at the rotor blades, insofar as they are not forces in the rotor blades themselves, also occur at the hub. Besides the (intentional) rotational forces, these involve inter alia also centrifugal forces and forces, loads and moments which arise out of the action of the wind on the rotor blades. Therefore the object of the present invention is to provide a rotor blade hub which, being of the required dimensions, satisfies all demands for reliable and safe operation of a wind power installation and which ensures secure and as inexpensive as possible transportation to the erection site of the wind power installation. A rotor blade hub for a rotor having at least one rotor blade, formed from at least two individual pieces.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a rotor blade hub for a wind powerinstallation.

2. Description of the Related Art

Such a hub represents a mechanical connection between the (horizontal)rotor shaft (rotor spindle) and the rotor blades. This means that allforces which occur at the rotor blades, insofar as they are not forcesin the rotor blades themselves, also occur at the hub. Besides the(intentional) rotational forces, these involve inter alia alsocentrifugal forces and forces, loads and moments which arise out of theaction of the wind on the rotor blades.

The rotor hub is accordingly one of the most highly loaded parts of awind power installation and, as the connection between the rotor bladesand the ‘rest of the installation’, it constitutes the component whosestrength must guarantee that no rotor blade can tear away from theinstallation.

Therefore in the state of the art in most cases rotor blade hubs areproduced as a whole from a casting, preferably a component consisting ofcast iron with spheroidal graphite.

BRIEF SUMMARY OF THE INVENTION

Therefore the object of the present invention is to provide a rotorblade hub which, being of the required dimensions, satisfies all demandsfor reliable and safe operation of a wind power installation and whichensures secure and as inexpensive as possible transportation to theerection site of the wind power installation.

The installations which are to be erected in the near future areattaining such dimensions that the required technical procedure for theintegral production of a rotor blade hub can scarcely still be properlycontrolled and the risk of weak locations, for example in the form ofblowholes is rising considerably. This means however that reliablemanufacture of fault-free rotor blade hubs is no longer possible.

Furthermore at least the transportation on land of large rotor bladehubs of corresponding dimensions can only be implemented at high(disproportionate) cost and necessitates extremely extensive logisticaland organization preparations.

The invention proposes that the rotor blade hub is produced in at leasttwo (individual) pieces and that the pieces are permanently assembled toform a rotor blade hub. The pieces can therefore be of such dimensionsthat transportation even overland can be performed using standardtransportation means.

In a preferred embodiment of the invention the number of the individualpieces of the rotor blade hub is at least one greater than the number ofrotor blades of the wind power installation. The individual pieces areof a size for which the known technical processes are reliablycontrolled. On the other hand, in that way division of the rotor bladehub into individual pieces is possible in such a fashion that the natureof the loading on the individual parts can be better taken into accountthan in the previously known configuration of the rotor blade hub in theform of a casting.

Particularly preferably the rotor blade hub is divided into a so-calledhub core and a number of outer hub portions corresponding to the numberof rotor blades. In that way each rotor blade can be fixed with a rootto an outer hub portion, in which case the outer hub portions are inturn mounted to the hub core so that the loading on the individualconnections can be clearly defined.

In a particularly preferred development of the invention provided bothon the hub core and also on the outer hub portions are fixing meanswhich permit a durable connection to be made between the outer hubportions and the hub core.

That durable connection can be afforded by screw or rivet connections.It is also possible to adopt a positively locking connection (forexample by welding, adhesive, assembling corresponding profiled andmutually matching parts (core and outer portion) (or a combination ofthe above-mentioned forms of connection)) of the hub core to the outerportions, in which respect care is to be taken to ensure that provisionis always made for a sufficiently strong connection between the hub coreand the outer portion.

Further preferred embodiments of the invention are described by thefeatures in the appendant claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

A possible embodiment of the invention is described in greater detailhereinafter. In the drawing:

FIG. 1 shows a front isometric view of a hub core and the outer hubportions which are shown separately therefrom,

FIG. 2 shows a side view of the hub core,

FIG. 3 shows a side view of an outer hub portion, and

FIG. 4 shows a side view of a hub.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a hub core 10 (being of a substantially triangularconfiguration in the view from the front thereof) with a bush 14 forreceiving the shaft trunnion (not shown). The rotor blade hub is fittedwith that bush 14 on to the rotor shaft (for example the shafttrunnion). Shown at a small distance from the hub core 10 are threeouter hub portions 12 which are (and remain) durably fixed to the hubcore 10 in the illustrated orientation and to which in turn the rotorblades (not shown) are fixed in known manner (see in that respect: ErichHau ‘Windkraftanlagen’ [‘Wind Power Installations’]).

In accordance with a preferred embodiment of the invention FIG. 1 showsa rotor blade hub for carrying three rotor blades. Accordingly the rotorblade hub has three outer hub portions, a respective one for theconnection of each rotor blade, and the hub core 10, as a fourthindividual piece of the rotor blade hub. This means that the rotor bladehub is formed from a number of individual pieces (which are assembledtogether), the number thereof being one greater than the number of rotorblades (not shown).

In order to achieve sufficient strength in respect of the materialinvolved, the individual pieces are preferably produced in a castingprocess and thus consist of cast iron of a suitable composition. In thatrespect the individual pieces are of a size in relation to which theproduction process thereof can be safely and properly controlled. It ispossible in that way to ensure that, as a consequence of trouble-freeindividual pieces, the rotor blade hubs produced therefrom also safelyand properly satisfy the high demands made.

FIG. 2 shows a side view of the hub core 10. In this case the view isdirectly on to a fixing flange 16 a (mounting) of substantially ovalshape with screw holes 16 for fixing an outer hub portion 12 to the hubcore 10. The screw holes 16 are arranged distributed over the flange 16a and the number is such that it is possible to make a secure connectionbetween the outer hub portion 12 and the hub core 10. FIG. 2 furthershows the rotor shaft bush 14 which can be seen through the opening inthe hub core (for bearing on the shaft trunnion). The fixing flange 16 adoes not necessarily have to be of an oval shape, it may also becircular or of a polygonal configuration.

FIG. 3 shows a view of an outer hub portion 12 from the side, whichafter assembly of the rotor blade hub 10, 12, 14, bears against theflange 16 a of the hub core 10. Also provided on that outer hub portion12 is a fixing flange 16 a of a substantially oval shape and havingopenings 16. In this respect the number and position of the screw holes16 correspond to those of the hub core 10 so that they are in exactlyopposite relationship in an assembled condition.

FIG. 3 further indicates a possible substantially circular rotor bladeconnecting means of the outer hub portion 12. In order to retain clarityof the Figure, fixing means have not been shown here.

For assembly of the rotor blade hub the outer hub portions 12 areapplied to the hub core 10 and, as soon as the outer hub portion 12 isin the correct position with respect to the hub core 10, the individualpieces 10, 12 are durably connected together by for example beingscrewed to each other. In that respect however all known technicalprocesses for connecting such individual pieces are possible, whilenon-releasable connecting methods such as for example welding andadhesive are also to be considered.

FIG. 4 shows an elevational view of a wind power installation with arotor blade hub 10 which carries three rotor blades 22. The rotor bladehub 10 is directly secured to the rotor member 26 of a generator and therotor member 26 of the generator rotates within the stator 24 of thegenerator. Both the hub 10 and also the rotor member 26 of the generatorare mounted rotatably on a shaft trunnion 28.

The illustrated wind power installation preferably involves a wind powerinstallation with a very high output, preferably more than three MW. Theassembled hub is of a diameter of more than 2.50 m (from the view asshown in FIG. 1).

1. A rotor blade hub for a rotor having at least one rotor blade, therotor blade hub comprising a hub core and at least one outer hub portionfor receiving a rotor blade, wherein the hub core and the at least outerhub portion each has a corresponding flange which is of substantiallyoval shape and by which the outer hub portion and the hub core areconnected together.
 2. A rotor blade hub as set forth in claim 1 whereinthe number of the individual pieces of the rotor blade hub is at leastone greater than the number of the rotor blades receivable by the hub.3. A wind power installation having a rotor blade hub as set forth inclaim
 1. 4. A process of producing a rotor blade hub from a wind powerinstallation from at least two individual pieces which are assembledtogether to form the hub, the process comprising: affixing to a hub coreat least one outer hub portion, the outer hub portion comprising fixingmeans for attaching a rotor blade to the outer hub portion, whereinaffixing said hub core and said outer hub portion comprises affixing apart of said outer hub portion having a substantially oval shape to apart of said hub core having a substantially oval shape.